i want to make my own power supply
the powe supply has three outputs(2 positive, 1 negative).
output voltage is 25V to 30 V @ 3A.
but i do not know what knid of power transformer to choose.
a secondary or multi secondary?
You say you want three outputs, but you only listed one. Tell us a little more and we might be able to help. I presume the input power is 120 VAC, 60 Hz?